Fineness of pictures displayed by prior art liquid crystal displays (LCDs) is determined by the pixel pitch. For example, 15-inch LCDs with a resolution of 1024×768 all have a pixel pitch of 0.297 mm or 0.30 mm, and 17-inch LCDs generally all have a pixel pitch of 0.264 mm. For mainstream mobile phone products currently available, the pixel pitch may even be as small as 0.1 mm and below, so they are able to display a very fine and realistic picture.
However, the too small pixel pitch also leads to associated problems in the production. For example, this leads to too high requirements on the exposure precision, and also makes the electrode wirings very thin to cause poor current signals, thus causing a too low yield of the highly fine liquid crystal panels. Seriousness of this problem has been proven by a practical case: because the highly fine display panels equipped in a type of mobile phones have a too low yield, this type of mobile phones is short of supply and it is very difficult to purchase such a mobile phone in the market.
As shown in FIG. 1, a schematic cross-sectional view of an LCD panel in the prior art is shown therein. In the prior art, the exposure precision of the pixel matrix manufacturing process has been very close to the limit, and increasing the resolution to a great extent with other process requirements remaining unchanged will have a serious effect on the yield.
The present inventor has noticed that, an advanced manufacturing technology for LCDs, which is termed as the color-filter-on-array (COA) technology, has come into use in the market. According to the COA technology, a color filter is formed on a thin film transistor (TFT) substrate; and the main advantage thereof is that the pixel aperture ratio and the displaying quality of the LCD can be improved, so it can be applied to high-level products. Furthermore, because it obviates the problem of alignment between the glass substrate of the color filter and the TFT substrate, the CELL process can be made easier.
For the COA technology, reference may be made to China Patent Application No. 02140119.5 published on Dec. 18, 2002, which discloses an electrode substrate for use in an LCD. According to this application, an array substrate comprises signal lines and control lines orthogonal to and on top of each other on a glass substrate. Near intersections between the signal lines and the control lines are disposed a plurality of TFTs. On the glass substrate, a color filter layer and pixel electrodes are stacked in sequence corresponding to the pixel regions surrounded by the signal lines and the control lines, and a strip-like colored region is formed by the pixel electrodes and the color filter layer.